Does my mailing list get uploaded?

No. The spreadsheet is parsed in your browser and the merge runs there too, which is the whole reason to do it this way: a mailing list is usually the most personal file in the job — names, addresses, amounts owed, sometimes medical or legal context.

Which data formats work?

CSV and TSV through the editor's own parser, which handles quoted fields and embedded newlines, plus JSON arrays and .xlsx or .ods spreadsheets. Mis-detected delimiters are visible in the preview table before you commit to anything.

Can it do labels and envelopes properly?

Yes. Nine Avery label stocks and eight envelope sizes are built in as real documents with the correct page setup, so the sheet that comes out lines up with the sheet in your printer rather than approximately.

Does it send the e-mails?

No, deliberately. The e-mail output writes one .eml draft per record, which your own mail application opens as a draft you review and send. Nothing here has a mail server, and a tool that silently sends a thousand messages is a tool that eventually sends the wrong thousand.

What happens to a record with an empty field?

The field prints nothing, and so does any text you attached to it as before-and-after text — which is how you avoid a letter that says “Dear ,” or a line reading “Reference:” with nothing after it. The rules can also skip a record entirely.

Mail Merge From a Spreadsheet, No Word Needed

Turn a CSV or spreadsheet and one letter into personalised letters, labels or envelopes — in your browser, with the data never leaving the machine it is on.